EDEN PRAIRIE, Minn. -- Even before the Minnesota Vikings lost Percy Harvin to another migraine episode on Thursday, they were exploring options to help their ailing receiving corps.

An NFL source said the team is bringing in former Tennessee and San Francisco receiver Brandon Jones for a workout on Friday.

Jones, 27, was waived by the 49ers on Wednesday after recovering from a hamstring injury. He reportedly visited the Seattle Seahawks on Thursday and has drawn interest from Oakland and Tennessee, among others.

The Vikings already have made one move this month because of a receiver shortage, signing first-year pro Freddie Brown off the street on Aug. 10. Now, with Harvin sidelined again indefinitely, Sidney Rice (hip) still on the active/physically unable to perform list and Jaymar Johnson waived/injured on Wednesday, the Vikings are down to only eight healthy receivers.

Jones (6-foot-1, 212 pounds) was a huge disappointment last season, catching only one pass for 18 yards in eight games after signing a five-year, $16.5 million contract with $5.4 million guaranteed.

But he was a serviceable No. 3 receiver for four seasons with the Titans, averaging 12.3 yards on 112 catches with nine touchdowns. He was timed at 4.38 seconds in the 40-yard dash coming out of Oklahoma in 2005, when he was the Titans' third-round pick (96th overall).

During Thursday's group installation period, the Vikings opened in a three-wide set consisting of Bernard Berrian, Greg Lewis and Logan Payne, who has replaced Johnson as the favorite for the No. 5 receiver job. If Jones signs, he'd be in the mix for that spot as well.

T-Jack's future

His chance to be the Vikings' starting quarterback usurped again, Tarvaris Jackson offered up an obvious observation.

"I'm not getting any younger," said Jackson, who will be 28 before the 2011 season begins.

"I feel like I was the best prepared this year that I've ever been. I felt great out there. I felt I knew what was going on. I felt confident in my abilities and my skill."

After starting 12 games in 2007, Jackson started only five in '08 and none last season, when he backed up Favre and threw only 21 passes. He received no offers as a restricted free agent this past offseason but remains hopeful his time is coming.

"Of course, one day I want to be a starter," Jackson said. "Hopefully, it's here, but if not, I understand the business and I understand how it works. So, right now, I'm just trying to get ready for this game this weekend."

Health watch

Rookie cornerback DeAndre Wright wasn't on the field a day after sustaining an apparent lower leg injury.

• Though coach Brad Childress indicated over the weekend MLB E.J. Henderson (leg) would play on Sunday at San Francisco, defensive coordinator Leslie Frazier said on Thursday no decision has been made. "We are still practicing and seeing how he progresses every day and every play," Frazier said. "We will talk about it again (Friday) after practice."

• Frazier echoed Childress' sentiments that E.J.'s brother, OLB Erin Henderson, was a pleasant surprise in his rare turn at middle linebacker at St. Louis. "He has done a good job in practice and we were wondering how he would do under the lights and he did a great job," Frazier said.

• PK Rhys Lloyd got his turn on field-goal attempts and hit 5 of 6, missing wide left from 45 yards. He's scheduled to handle all kicking duties in the first half on Sunday.